High strength laminated amino plastics



Oct. 30, 1945. K. E. RlPPER HIGH STRENGTH LAMINATED AMINO PLASTICS FiledAug FIG INVENTOR. Al/W7' E. F/PPEF,

Patented Oct. 30, 1945 Kurt E. Ripper, Bronxville, N. American CyanamidCompany,

a corporation of) Maine Application August 17, 1940, Serial No, 353,15

claims. (Cl. 154-48) This invention relates to laminated materialsbonded with synthetic resins and more particularly `to increasing thestrength of such materials. u Previously various laminated materialshave been made by the impregnation of sheets of paper or layers offabric with a synthetic resin and ical strength whemthey are reinforcedwith pai per or fabric laminae than when they are merely mixed withcellulosic fibers not in the form of paper of fabric. In other words thevreinforcing effect of the cellulosic filler in fabricated form (paperor cloth) is practically lost when it is associated with amino plastics.The problem of producingA amino plastic materials of especially highmechanical strength has been a problem of long standing.

are reinforced An object of this invention is to provide amino plasticresins of high mechanical strength.

. A more particular object of this invention is to increase themechanical strength of amino Plastic bonded laminated materials.

These and other objects are attained by forming an assembly including aplurality of layers of textile fabric or paper and one or more layers ofglass cloth and bonding the assembly together with an amino plasticresin.

Figure 1 of the drawing is a perspective of a laminated material,alternate layers of which are glass cloth and paper, the laminae beingseparated. at one corner for purposes oi illustration.

Figure 2 illustrates a section of the laminated material which forms oneembodiment'of my intion. l

The following examples in which the propor- Y., assigner to NCW Yl'k, N.Y.,

tions are in parts by weight arehgiven by way of illustration and not inlimitation.

' Example 1 Sheets of paper and sheets of glass cloth (0.01 inch thick)are impregnated with a melaminemodied dicyandiamide-formaldehyde resinsyrup (Resin A). The impregnated paper and glass cloth are dried andpartially polymerized by placing in an oven at a temperature of about'10"4 C. for about fifteen to thirty minutes. The glass cloth ispreferably placed horizontally because of the tendency of the resinsyrup to run off of the sheet inv a vertical position. The impregnatedpaper contains about 55% of resin solids before pressing while the glasscloth contains about 2'1%'50% of resin solids before pressing.

A laminated plate which comprises six sheets of the impregnated paper 6,which are stacked with alternate layers (5 sheets) of the impregnatedglass cloth 1, as illustrated in Figure l. The assembly of paper andcloth is placed between hot platens at a temperature of l45 C. andsubjected to a pressure of about 2000 pounds per square inch for aboutthirty minutes. The resulting laminated plate I is very homogeneous and.contains about 30% of resin solids. The impact strength is about 262 cm.kg./cm.2 while the bending strength is about 2,194 kgJcm?. Y

The ,values obtained withv the laminations containing glass cloth andpaper` arranged alternately show extremely high mechanical strengthvalues as compared to paper alone. The impact strength of similar paperbase laminated materials impregnated with the same resin and using thesame general procedure as outlined above is about 10-11 cm. kg./cm.2 andthe bending strength in lig/cm.2 is only about 1108. Thus the impactstrength is increased around twenty-live times whereas the bendingstrengthl is approximately doubled by the use of the4 glass cloth.

Example Z' Paper sheets and glass cloth are impregnated as described inExample 1 and an assembly is made of six of the former to three of thelatter. The paper sheets 6 and the glass cloth 1 are stacked together toform the assembly 2 illustrated in Figure 2. This assembly is molded atabout 140145 C. and under about 2000 pounds per square inch pressure forabout one half hour. The resulting homogeneous laminated plate containsabout 39% of resin solids and shows an impact strength of approximately266 cm. kg./crn.2

and a bending strength of about 1950 Example 3 Paper sheets and glasscloth are impregnated in the same manner as set forth in Example 1 andan assembly of six paper sheets and two glass cloth sheets is made ofsix of the former to two of the latter. Figure 3 shows the manner ofarranging the sheets of paper 6, and the glass cloth of 250 cm. lig/cm.2about 1880 ken/cm?.

Example 4 An assembly made according to Example 3 con.v

taining the same synthetic resin is molded at pounds per square inchpressure between hot platens at a temperature of 140145' C. for aboutone half hour. The impact strength of the product is 250 cm. kg./cm.2,or in other words about the same strength as the product of Example 3.

Example 5 Paper sheets and glass cloth are impregnated in the samemanner as set forth in Example 1 and an assembly d of six paper sheets 6and one glass cloth sheet l is made .up in the manner as illustrated inFigure 4. This assembly is about thirty minutes. A homogeneous laminatedplate is obtained which has an impact strength of about 194 cm. lig/cm?and a bending strength of 1485 lig/Cm?.

Example 6 v Example 4 is repeated substituting amixed mel- 50-urea-formaldehyde resin (Resin B) hated plate having an impact strengthof about kg./cm.2 as compared to an impact strength of about 21 cm.kg./cm.2 f or a material bonded with the same resin but not having glasscloth incorporated therein.

Example 7 Example 4 is repeated substituting urea-thiourea-formaldebyderesin (Resin C) for the melamine modied dicyandiamide-formaldehyderesin. A laminated product is obtained which is quite homogeneous andwhich has an impact strength of 4about 184 cm. lig/cm?. product madewith the same resin the glass cloth has an impact strength of about 30om. kgJem. Generally urea-thiourea-formaldehyde laminated papermaterials have an impact strength of only about 11-13 cm. kg./cm.2.Resin A may be prepared by reacting dicyandiamide and a minor proportionof melamine with an aldehyde such duce a clear syrup as described in mycopending applications Serial Nos. 311,935, 328,741 and as formaldehydeto pro-` 331,161. Resin "A" scribed in my copending application SerialNo.

to 5 inclusive pertain to melamine modiied dicyandiamide-formaldehydereslowing procedure: 240 parts of formalin (an aqueous solutioncontaining 37% formaldehyde by weight) is adjusted to pH of 6.42 (glasselec- Resin C may be prepared by any convenient the preparation ofurea-thioureaformaldehyde resin Syrups. The resin used in parts of 10%60 parts of urea are reacted at about 40 solution of triethylamine.

added and the mixture is C. for an additional hour by the addition ofabout 10 of salicyclic acid plete the reaction and/or polymerizationduring the drying and hardening of Other amino plastic res be added tothe resins.

My invention utilizing glass cloth as a reinamples. paper and cloth orcombinations of various kinds used in place of the paper in the Thismodication of my invention is illustrated in Figure 5 Where the assembly5 is composed cf layers of canvas cloth V8 and a layer of glass cloth l.The glass cloth and canv' for the purposes vas may also be arranged asillustrated in Figures 1-4 inclusive with the expectation that thecanvas cloth is substituted for the paper.

Glass cloth having substituted for that used in the above examples.Glass cloth is commercially available in thicknesses ranging from about0.002 inch to 0.015 inch. but the use of glass cloth of other dimensionsis also withinthe lscope of this invention. It has generally been foundthat glass cloth having a thickness of around 0.01 inch is well suitedof this invention since material thinner than this does not form quiteas good a bond whereas material thicker than this is not so economicaland the use thereof usually has little advantage over the use of the0.01 inch thick cloth.

In some instances I have found that it is convenient to impregnate theglass cloth with a resin different from the impregnating resin used forthe paper or fabric cloth with which the glass cloth is associated. Forexample, the glass cloth may be bonded with a dicyandamide-iormaldehyd@resin, preferably m'oded with a minor proportion of melamine and thepaper or other fabric tobe used in the lamination is impregnated with amelamine-formaldehyde resin, a urea-formaldehyde resin, etc.

The term glass cloth as used herein is intended to cover not only woven,knitted, ielted and braided types of materials'but also thin foraminoussheets of glass. The terni E19S$" iS intended to cover all types ofglass including the so-called silica glass.

The procedure illustrated for the production of laminated plates is alsoadaptable for laminating materials in other forms, e. g. tubes. rods,etc. as well as for shaping in a mold.

Obviously many modiilcatlons may be made in the compositions andprocesses described without departing from the spirit and scope o! theimention as described in the appended claims.

claim:

various thicknesses may be 1. A relatively rigidplaminated article whichhas been consolidated by heat and pressure comprising an assembly ers ofcellulosic tlbrous material and embedded therein atleast one layer ofglass cloth, between at least two sheets of said brous material, theassembly being bonded with a synthetic. thermosetting amino plasticresin.

2. A relatively rigid laminated article which has been consolidated byheat and pressure comprising an assembly including a plurality ot layersof cellulosic fibrous material and embedded therein at least one layerot glass cloth between at least two sheets of said brous material, theassembly being bonded with dicyandiamide-formaldehyde resin.

3. A relatively rigid laminated article which has been consolidated byheat and pressure comprising an assembly including a plurality oi'layers of cellulosic fibrous material and embedded therein at least onelayer of glass cloth between at least two sheets of said brous material.the assembly being bonded with dicyandiamide-formaldehyde resin modiiiedwith a minor proportion of melamine.

4. A relatively rigid laminated article which has been consolidated byheat and pressure comprising an assembly including a plurality of layersof cellulosic 'fibrous material and embedded therein at least one layerof glass cloth between at least two sheets of said brous material, theassembly being bonded with melamine-formaldehyde resin.

5. A relatively rigid laminated article which has been consolidated byheat and pressure come prising an assembly including a plurality oflayers of cellulosic fibrous material and embedded therein at least onelayer of glass cloth between at least two sheets of said iibrousmaterial, the

m assembly be'ing bonded with a urea-formaldehyde resin.

KURT E. RIPPER.

including a plurality ot ln!-`

